1. Synthesis of the N,N&#8217;-(alkane-1,n-diyl)diisonicotinamide
<ol>
	<li>Dry a single neck or three-neck round bottom flask in an oven (100 &#186;C, 1 hr) to ensure all moisture is removed.</li>
	<li>Add solid isonicotinic acid, or its derivative, to the flask along with a magnetic stirring bar. If the diaminoalkane ligand(s) are solids at room temperature, then 0.5 mole&#160;(to the number moles of isonicotinic acid) is added to the flask at this stage.</li>
	<li>Cap the neck(s) of the flask with rubber se...

<ol>
	<li>Wheate, N. J., Walker, S., Craig, G. E., Oun, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+status+of+platinum+anticancer+drugs+in+the+clinic+and+in+clinical+trials.">The status of platinum anticancer drugs in the clinic and in clinical trials.</a> Dalton Trans. 39, 8113-8127 (2010).</li><li>Kiernan, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pain+with+platinum:+oxaliplatin+and+neuropathy.">The pain with platinum: oxaliplatin and neuropathy.</a> Eur. J. Cancer. 43, 2631-2633 (2007).</li><li>Markman, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+features+of+hypersensitivity+reactions+to+carboplatin.">Clinical features of hypersensitivity reactions to carboplatin.</a> J Clin. Oncol. 17, 1141-1145 (1999).</li><li>Ding, D., Allman, B. L., Salvi, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review:+Ototoxic+characteristics+of+platinum+antitumor+drugs.">Review: Ototoxic characteristics of platinum antitumor drugs.</a> Anatomical Rec. 295, 1851-1867 (2012).</li><li>Galluzzi, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+mechanisms+of+cisplatin+resistance.">Molecular mechanisms of cisplatin resistance.</a> Oncogene. 31, 1869-1883 (2012).</li><li>Park, G. Y., Wilson, J. J., Song, Y., Lippard, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phenanthriplatin,+a+monofunctional+DNA-binding+platinum+anticancer+drug+candidate+with+unusual+potency+and+cellular+activity+profile.">Phenanthriplatin, a monofunctional DNA-binding platinum anticancer drug candidate with unusual potency and cellular activity profile.</a> Proc. Natl. Acad. Sci. USA. 109, 11987-11992 (2012).</li><li>Moghaddas, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=next+generation+platinum+antitumor+agents:+A+paradigm+shift+in+designing+and+defining+molecular+targets.">next generation platinum antitumor agents: A paradigm shift in designing and defining molecular targets.</a> Inorg. Chim. Acta. 393, 173-181 (2012).</li><li>Farrell, N. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platinum+formulations+as+anticancer+drugs+clinical+and+pre-clinical+studies.">Platinum formulations as anticancer drugs clinical and pre-clinical studies.</a> Curr. Top. Med. Chem. 11, 2623-2631 (2011).</li><li>Wheate, N. J., Collins, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-nuclear+platinum+complexes+as+anti-cancer+drugs.">Multi-nuclear platinum complexes as anti-cancer drugs.</a> Coord. Chem. Rev. 241, 133-145 (2003).</li><li>Gourley, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+phase+I+study+of+the+trinuclear+platinum+compound,+BBR3464,+in+combination+with+protracted+venous+infusional+5-fluorouracil+in+patients+with+advanced+cancer.">A phase I study of the trinuclear platinum compound, BBR3464, in combination with protracted venous infusional 5-fluorouracil in patients with advanced cancer.</a> Cancer Chemoth. Pharmacol. 53, 95-101 (2004).</li><li>Calvert, A. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+II+clinical+study+of+BBR3464,+a+novel,+bifunctional+platinum+analogue,+in+patients+with+advanced+ovarian+cancer.">Phase II clinical study of BBR3464, a novel, bifunctional platinum analogue, in patients with advanced ovarian cancer.</a> Eur. J. Cancer. 37, (2001).</li><li>Jodrell, D. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+II+studies+with+BBR3464,+a+novel+tri-nuclear+platinum+complex,+in+patients+with+gastric+or+gastro-oesophageal+adenocarcinoma.">Phase II studies with BBR3464, a novel tri-nuclear platinum complex, in patients with gastric or gastro-oesophageal adenocarcinoma.</a> Eur. J. Cancer. 40, 1872-1877 (2004).</li><li>William, W. N., Glisson, B. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+strategies+for+the+treatment+of+small-cell+lung+carcinoma.">Novel strategies for the treatment of small-cell lung carcinoma.</a> Nat. Rev. Clin. Oncol. 8, 611-619 (2011).</li><li>Raynaud, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=cis-Amminedichloro(2-methylpyridine)+Platinum(II)+(AMD473),+a+novel+sterically+hindered+platinum+complex:+In+vivo+activity,+toxicology,+and+pharmacokinetics+in+mice.">cis-Amminedichloro(2-methylpyridine) Platinum(II) (AMD473), a novel sterically hindered platinum complex: In vivo activity, toxicology, and pharmacokinetics in mice.</a> Clin. Cancer Res. 3, 2063-2074 (1997).</li><li>Holford, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=biochemical+and+pharmacological+activity+of+the+novel+sterically+hindered+platinum+co-ordination+complex+cis-[amminedichloro(2-methylpyridine)]+platinum(II)+(AMD473).">biochemical and pharmacological activity of the novel sterically hindered platinum co-ordination complex cis-[amminedichloro(2-methylpyridine)] platinum(II) (AMD473).</a> Anti-Cancer Drug Des. 13, 1-18 (1998).</li><li>Munk, V. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigations+into+the+interactions+between+DNA+and+conformationally+constrained+pyridylamine+platinum(II)+analogues+of+AMD473.">Investigations into the interactions between DNA and conformationally constrained pyridylamine platinum(II) analogues of AMD473.</a> Inorg. Chem. 42, 3582-3590 (2003).</li><li>Wheate, N. J., Collins, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-nuclear+platinum+drugs:+A+new+paradigm+in+chemotherapy.">Multi-nuclear platinum drugs: A new paradigm in chemotherapy.</a> Curr. Med. Chem. - Anti-Cancer Agents. 5, 267-279 (2005).</li><li>Beale, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+phase+I+clinical+and+pharmacological+study+of+cis-diamminedichloro(2-methylpyridine)+platinumm+II+(AMD473).">A phase I clinical and pharmacological study of cis-diamminedichloro(2-methylpyridine) platinumm II (AMD473).</a> British journal of cancer. 88, 1128-1134 (2003).</li><li>Sessa, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+and+pharmacological+phase+I+study+with+accelerated+titration+design+of+a+daily+times+five+schedule+of+BBR3464,+a+novel+cationic+triplatinum+complex.">Clinical and pharmacological phase I study with accelerated titration design of a daily times five schedule of BBR3464, a novel cationic triplatinum complex.</a> Ann. Oncol. 11, 977-983 (2000).</li><li>Brown, S. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+aspects+of+the+platinum+anticancer+drugs+picoplatin+and+BBR3464+to+synthesize+a+new+family+of+sterically+hindered+dinuclear+complexes;+their+synthesis,+binding+kinetics+and+cytotoxicity.">Combining aspects of the platinum anticancer drugs picoplatin and BBR3464 to synthesize a new family of sterically hindered dinuclear complexes; their synthesis, binding kinetics and cytotoxicity.</a> Dalton Trans. 41, 11330-11339 (2012).</li><li>Still, B. M., Anil Kumar, P. G., Aldrich-Wright, J. R., Price, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=195Pt+NMR+-+Theory+and+application.">195Pt NMR - Theory and application.</a> Chem. Soc. Rev. 36, 665-686 (2007).</li><li>Wheate, N. J., Cullinane, C., Webster, L. K., Collins, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis,+cytotoxicity,+cell+uptake+and+DNA+interstrand+cross-linking+of+4,4'-dipyrazolylmethane-linked+multinuclear+platinum+anti-cancer+complexes.">Synthesis, cytotoxicity, cell uptake and DNA interstrand cross-linking of 4,4'-dipyrazolylmethane-linked multinuclear platinum anti-cancer complexes.</a> Anti-Cancer Drug Des. 16, 91-98 (2001).</li></ol>

In this work dinuclear platinum complexes have been synthesized as potential anticancer agents. In doing so bispyridine bridging ligands were synthesized via an amide coupling reaction using isonicotinic acid and variable length diaminoalkanes. Previously the synthesis of bispyridine ligands and their methyl analogues with 2 to 8 methylene groups and their respective platinum complexes have been reported. In this paper, the synthesis and purification method has been revised making it faster and cheaper and have demonstra...

Platinum anticancer drugs remain one of the most widely used family of agents in the treatment of human cancer1. Despite their success, they are limited in their application by severe dose-limiting side effects2-4. The limited doses that can be administered to patients also means that tumors can develop resistance5. As such, new drugs continue to be developed to improve the side effect profile and overcome acquired resistance, like phenanthriplatin6 and phosphaplatin7.
In the late 1990s, a trinuclear platinum drug was developed, BBR3464 (Scheme 1)8, that is up to 1,000x&#160;more cytotoxic in vitro than the leading platinum drug, cisplatin. BBR3464 is also able to overcome acquired resistance in a panel of human cancer cell lines9. Unfortunately, the increased activity of BBR3464 is matched by 50- to 100- fold higher toxicity, which limits its use10-12. It is also easily degraded in the body, meaning little of the drug reaches cancer nuclei intact9.
Picoplatin is a mononuclear platinum-based drug that contains a 2-methyl-pyridine ligand (Scheme 1)13. The methyl group of this drug protects it from attack by biological nucleophiles; in particular cysteine and methionine containing peptides/proteins14-16. As such, the drug is quite stable and has a much higher concentration that reaches cancer nuclei compared with both BBR3464 and cisplatin17. Its reduced reactivity also means picoplatin has a higher maximum tolerated dose compared with BBR3464 and cisplatin10,18,19.
This project therefore sought to combine the properties of BBR3464 and picoplatin to produce new drugs that are able to overcome acquired resistance that display improved biological stability and less severe side-effects (e.g., Figure 1). In doing so, a range of dinuclear platinum complexes were prepared with bispyridine bridging ligands20. The ligands are made using amide coupling reactions with isonicotinic acid, or its derivatives like 2-methyl-isonicotinic acid, variable length diaminoalkanes. Reaction of one mole equivalent of the ligands with two mole equivalents of transplatin yields the desired platinum complexes (Scheme 1).

<table border="0" cellpadding="0" cellspacing="0" width="782">
	<tbody>
		<tr height="24">
			<td height="24" style="height:24px;width:297px;">D2O</td>
			<td style="width:175px;">Aldrich</td>
			<td align="right" style="width:159px;">151882</td>
			<td style="width:152px;">99.9% D</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:297px;">DMSO-d6</td>
			<td style="width:175px;">Aldrich</td>
			<td align="right" style="width:159px;">156914</td>
			<td style="width:152px;">99.96% D</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:297px;">1,8-diaminooctane</td>
			<td style="width:175px;">Aldrich</td>
			<td style="width:159px;">D22401</td>
			<td align="right" style="width:152px;">98%</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:297px;">1,10-diaminodecane</td>
			<td style="width:175px;">Aldrich</td>
			<td style="width:159px;">D14204</td>
			<td align="right" style="width:152px;">98%</td>
		</tr>
		<tr height="80">
			<td height="80" style="height:80px;width:297px;">1,12-diaminododecane</td>
			<td style="width:175px;">Aldrich</td>
			<td style="width:159px;">D1,640-1</td>
			<td align="right" style="width:152px;">98%</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:297px;">Isonicotinic acid</td>
			<td style="width:175px;">Aldrich</td>
			<td style="width:159px;">I17508</td>
			<td align="right" style="width:152px;">99%</td>
		</tr>
		<tr height="120">
			<td height="120" style="height:120px;width:297px;">1-Propylphosphonic anhydride solution</td>
			<td style="width:175px;">Aldrich</td>
			<td align="right" style="width:159px;">431303</td>
			<td style="width:152px;">50 wt% in ethyl acetate</td>
		</tr>
		<tr height="100">
			<td height="100" style="height:100px;width:297px;">Trans-diaminodichloridoplatinum(II)</td>
			<td style="width:175px;">Aldrich</td>
			<td style="width:159px;">P1525</td>
			<td style="width:152px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Dimethylsulfoxide</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:159px;">Z76855</td>
			<td style="width:152px;">&#62;99.9%, anhydrous</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">N,N&#8217;-dimethylformamide</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td align="right" style="width:159px;">227056</td>
			<td style="width:152px;">99.8%, anhydrous</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Triethylamine</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:159px;">T0886</td>
			<td style="width:152px;">&#62;99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Nylon filter membranes</td>
			<td style="width:175px;">Whatman</td>
			<td style="width:159px;">7402-004</td>
			<td style="width:152px;">Pore size, 0.2 &#181;m</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Equipment</td>
			<td style="width:175px;"></td>
			<td style="width:159px;"></td>
			<td style="width:152px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Magnetic stirring hotplate</td>
			<td style="width:175px;"></td>
			<td style="width:159px;"></td>
			<td style="width:152px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Magnetic stirring bar&#160;</td>
			<td style="width:175px;"></td>
			<td style="width:159px;"></td>
			<td style="width:152px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Round bottom or three neck flask</td>
			<td style="width:175px;"></td>
			<td style="width:159px;"></td>
			<td style="width:152px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:297px;">Rubber septums of sufficient size for chosen round bottom or three neck flask</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">5 mL hypodermic syringes</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Hypodermic needles</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Rubber party ballons</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Rubber bands</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:297px;">A source of N2 gas</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Rotary evaporator</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Drying oven</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">NMR tubes</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">NMR spectrometer</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">500 mL beakers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:297px;">Glass or plastic pipettes</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

amide coupling reaction for the synthesis of bispyridine-based ligands and their complexation to platinum as dinuclear anticancer agents

Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. Isonicotinic acid, or its derivatives, are coupled to variable length diaminoalkane chains under an inert atmosphere in anhydrous DMF or DMSO with the use of a weak base, triethylamine, and a coupling agent, 1-propylphosphonic anhydride. The products precipitate from solution upon formation or can be precipitated by the addition of water. If desired, the ligands can be further purified by recrystallization from hot water. Dinuclear platinum complex synthesis using the bispyridine ligands is done in hot water using transplatin. The most informative of the chemical characterization techniques to determine the structure and gross purity of both the bispyridine ligands and the final platinum complexes is 1H NMR with particular analysis of the aromatic region of the spectra (7-9 ppm). The platinum complexes have potential application as anticancer agents and the synthesis method can be modified to produce trinuclear and other multinuclear complexes with different hydrogen bonding functionality in the bridging ligand.

The bispyridine ligands and their respective dinuclear platinum complexes are characterized by 1H, 13C and 195Pt NMR (Tables 1 and 2), and electrospray ionization mass spectroscopy. Accurate melting points can be determined using differential scanning calorimetry and purity is best determined by elemental analysis for C, H and N percentage content. Of most use is 1H NMR as it is quick and easy to use, giving results within minutes of isolation ...

Watch this Scientific Journal Video about Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents at JoVE.com

Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents

This protocol describes the use of amide coupling reactions of isonicotinic acid and diaminoalkanes to form bridging ligands suitable for use in the synthesis of multinuclear platinum complexes, which combine aspects of the anticancer drugs BBR3464 and picoplatin.

Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. ...

amide-coupling-reaction-for-synthesis-bispyridine-based-ligands-their

Research

JoVE Journal

Chemistry

13.8K Views.  The University of Sydney. This protocol describes the use of amide coupling reactions of isonicotinic acid and diaminoalkanes to form bridging ligands suitable for use in the synthesis of multinuclear platinum complexes, which combine aspects of the anticancer drugs BBR3464 and picoplatin.